In typical gas and light oil-fueled utility burners, the gas/oil is ignited from a pilot flame on an ignitor. The ignitor must start this pilot flame. Therefore, it creates a spark from a spark rod connected to a high voltage transformer. The transformer provides high voltage electrical power (about 8 kV) to the spark rod that is adjacent to a grounded metal housing. The electrical power causes an arc (spark) to be produced between the spark rod and housing (ground). This arc occurs for a predefined time (typically 10 seconds) when the ignitor is first turned on. In prior art devices there are no external verifications that arcing is actually occurring.
The ignitor also has a flame rod located near a small fuel source, the spark rod and the housing. The spark rod creates arcing that lights the fuel from the small fuel source creating the pilot flame. The pilot flame spans the area between the flame rod and the housing. Since fire conducts electricity, this causes current to flow from the flame rod to the housing through the flame.
This current is monitored by an externally mounted electronic device. The electronic device and flame rod are referred to as a flame-proving device. The flame-proving device analyzes the flow of current from the flame rod to the housing to determine the presence of a pilot flame.
The arc from the high voltage transformer sometimes interferes with the ignitor flame-proving device, causing it to falsely indicate flame while the arc is on.
When an ignitor will not correctly light a pilot flame, the technician diagnosing the problem will usually remove the ignitor from the boiler and activate it without fuel to visually determine if an arc is being produced. This takes time and effort.
Currently, there is a need for a device that automatically determines if an ignitor is producing arcing and more accurately determines if a pilot flame is being produced.